DOUBLE IMPACT : Interplanetary shock wave and CME :Earth's magnetic field is reverberating in response to a pair of impacts on Sept. 30th. A weak interplanetary shock wave hit Earth at 10:25 UT followed by a stronger CME strike at approximately 22:30 UT. Observers in Norway are reporting significant ground currents, while the Arctic Circle is glowing with Northern Lights. High-latitude sky watchers should be alert for auroras, especially during the hours around local midnight.